Bi-phase fluid surge suppressor device

ABSTRACT

A siphon guard includes a housing having an inlet and an outlet. A primary flow path is disposed within the housing and is in fluid communication with the inlet and the outlet. A secondary flow path is disposed within the housing and is in fluid communication with the inlet and the outlet. The secondary flow path has a higher resistance to fluid flow than the primary path. A valve is disposed within the primary flow path. The valve has a valve seat and a first ball and a second ball. The first ball is movable by gravity between a valve closed position, where the first ball is in contact with the valve seat, and a valve open position, where the first ball is spaced from the valve seat. The first ball is disposed between the second ball and the valve seat. The second ball is movable by gravity between a valve closed position and a valve opened position.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention generally relates to devices used in the treatmentof hydrocephalus, and more particularly, to improvements to shunts andsiphon control devises used to help divert and regulate excess fluidduring the treatment therapy.

2. Description of the Related Art

The human brain includes four ventricles. Each ventricle contains achoroid plexus that produces cerebrospinal fluid (CSF) which bathes andcushions the brain and spinal cord within their bony and non-elasticconfines.

In a normal healthy person, CSF continuously circulates through andaround the brain and its ventricles and around the spinal cord and iscontinuously drained away into the circulatory system so that acontrolled pressure is continually maintained within the system. The CSFflows from the lateral ventricles via the foramina of Monro into thethird ventricle, and then the fourth ventricle via the cerebral aqueductin the brainstem. From there it normally can pass into the central canalof the spinal cord or into the cisterns of the subarachnoid space viathree small foramina: the central foramen of Magendie and the twolateral foramina of Luschka.

The aqueduct between the third and fourth ventricles is very small, asare the foramina and both are therefore susceptible to becoming blockedor restricted, commonly due to a birth defect, or a local growth, suchas that caused by a tumor or infection, thereby disrupting the normalCSF flow. When the CSF flow is impeded, the continued production of CSFwill cause an increase in intracranial pressure as the fluid collectswithin the ventricles.

Alternatively, a similar increase in intracranial pressure of thepatient may result from an overproduction of the CSF fluid, from acongenital malformation, or from complications of head injuries orinfections, or in some cases, by malabsorption. In any case, the resultis the same, an increase of CSF fluid within the ventricles and anincrease in intracranial pressure. This condition is calledhydrocephalus.

When the CSF accumulates in the cerebral ventricles, the increasedvolume of fluid compresses the patient's brain tissue since thepatient's skull will not yield to this unplanned expansion of fluid.Unfortunately, this compression destroys more and more brain tissue anda variety of secondary symptoms will become apparent in the patient asthe neurological functions effectively shut down. These include,headaches, vomiting, dizziness, slurred speech, photophobia/lightsensitivity, and in more severe cases, seizures, loss of consciousnessand even death.

Hydrocephalus is often treated by the insertion of a diverting catheterinto the ventricles of the brain or into the lumbar cistern. Such acatheter or shunt is connected by a regulating valve to a distalcatheter which shunts the CSF to another space where it can bereabsorbed and the excess pressure within the brain released. Examplesof common diversion sites include the peritoneum of the abdomen via aventriculoperitoneal shunt or lumboperitoneal shunt or the atrium of theheart via a ventriculoatrial shunt.

A commonly used shunt to treat hydrocephalus is called the Spitz-Holtershunt. It is a conduit that is positioned between the patient's brainand the patient's heart. The device includes a tiny one-way valve thatallows a controlled amount of CSF to leave the lateral ventricle of thebrain and enter the heart and thereby prevent the increased pressurethat causes such damage to the tissues of the brain. This device hashelped millions survive this potentially fatal condition since the late1950s.

About 50% of the shunts fail within the first 5 years after implantationindependent of the shunt operating principle and the hydrocephalusetiology. Such shunt failure requires a revision of the shunt systemwithin the patient to avoid a return of original hydrocephalus symptoms.The main causes of failure are infection of the shunt system,obstruction of the shunt, and over-drainage and under-drainage of CSFwithin the shunt system.

Over-drainage results in an excessive average flow of CFS through theshunt system. This condition may generate an abnormally lowintra-cranial pressure, a collapse of the parenchyma and sub-arachnoidhemorrhage.

Some shunt systems use a “Codman® Hakim® valve” or a “Codman® Certas™”programmable valve, which are commercially available from Codman &Shurtleff, Inc. of Raynham, Mass. The Codman® Hakim® and the Codman®Certas™ valve allows a doctor to adjust the valve opening pressurenon-invasively after implantation.

Effective fluid flow rate control is particularly important sinceover-drainage of cerebrospinal fluid can result in dangerous conditions,including subdural hematoma. Over-drainage tends to occur when a patientmoves from a horizontal position to a sitting or standing position, dueto a siphon effect in the shunt system. To reduce the risk ofover-drainage, some shunt systems include additional devices, sometimesreferred to as anti-siphon devices, for preventing over-drainage. Somesuch devices use weights, which move in response to the patient changingposition, to open or close the fluid flow path. One system, described inU.S. Pat. No. 5,368,556 (Lecuyer), includes spherical weights whichprovide additional compressive force against a valve spring to helpmaintain the valve in a closed position when the patient is sitting orstanding. However, noise associated with the use of such weights may beobjectionable. Other systems, such as the SIPHONGUARD® Anti-Siphon andFlow-Control Device, as described in U.S. Pat. No. 6,126,628, provides adual pathway, ball and spring anti-siphon device. The primary pathway iscontrolled by a ball 110 that is biased by a flat spring bias element114 and a coil spring counterbias element 112.

For a shunt system with a differential pressure (DP) valve set to 100mmH₂O and connected to a simple gravity actuated valve that requires 200mmH₂O to open in the vertical position. The valve is calibrated to addeither 0 mmH₂O when horizontal or 200 mmH₂O when in the verticalposition. Fluid will be driven through the system and into theperitoneal (distal) catheter to drain when the differential pressureexceeds the threshold 100 mmH₂O (DP valve setting) in the horizontalposition or 300 mmH₂O (100 mmH₂O valve+200 mmH₂O anti-siphon device)when in the vertical position. The anti-siphon device will thereforeprevent any fluid drainage until the 300 mmH₂O threshold is exceeded.

A drainage problem manifests itself when a patient is not completelyvertical (i.e. sleeping on a pillow or bedridden), due to gravity theweighted balls will close off the single fluid pathway and prevent fluiddrainage, causing a potentially high increase in the patients ICP suchthat severe headaches develop, or worse. This will continue until thethreshold pressure of 300 mmH₂O is exceeded or the anti-siphon devicebecomes oriented in the horizontal position to open the single fluidpathway.

With the proposed Bi-Phase Fluid Surge Suppressor device, the abovedrainage problem is mitigated. With a Bi-Phase valve set to 200 mmH₂O(in the vertical position), and one has a differential pressure (DP)valve set to 100 mmH₂O. When the patient is positioned such that theweighted balls of the Bi-Phase device close the primary pathway, thealways open higher resistive secondary pathway allows CSF fluid to drain(when the threshold DP of 100 mmH₂O only is exceeded).

Should a patient stand upright (vertical position), the entire systemwould control the hydrostatic siphoning effect until the threshold of300 mmH₂O (100 mmH₂O DP valve+200 mmH₂O Bi-Phase device) is exceeded.Once exceeded, the Bi-Phase device continues to suppress the surge offluid until the pressure decreases and the weighted balls seatthemselves to close off the primary pathway, while still allowing slowgradual drainage through the secondary pathway until the differentialpressure falls below the 100 mmH₂O DP valve setting, in this example.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of view of a shunt system in accordancewith the present invention;

FIG. 2 is an exploded view of the siphon control device in accordancewith the present invention;

FIG. 3A is a cross-sectional view of the siphon control device inaccordance with the present invention showing fluid flowing through boththe primary and secondary flow paths;

FIG. 3B is a cross-sectional view of the siphon control device inaccordance with the present invention showing fluid flowing through onlythe secondary flow path;

FIG. 3C is a cross-sectional view of the siphon control device inaccordance with the present invention showing fluid flowing through boththe primary and secondary flow paths;

FIG. 4 is a cross-sectional view taken along line 4-4 of FIG. 3A andlooking in the direction of the arrows;

FIG. 5 is a cross-sectional view taken along line 5-5 of FIG. 3A andlooking in the direction of the arrows;

FIG. 6 is a cross-sectional view taken along line 6-6 of FIG. 3A andlooking in the direction of the arrows;

DETAILED DESCRIPTION OF THE PRESENT INVENTION

Referring now to FIGS. 1-6, a shunt system 10 is illustrated. Shuntsystem 10 includes a proximal catheter 12, a shunt valve 14, a siphoncontrol device 16 and a distal catheter 18. Proximal catheter 12 is apiece of tubing that is introduced in the ventricle of the brain via aburr hole 20 in the skull as shown in FIG. 1. Proximal catheter 18 has aplurality of through holes 22 at its distal end to permit CSF to enterinto the proximal catheter 18 and to be drained from the ventricle. Theproximal end of proximal catheter 18 is connected to the housing 24 ofshunt valve 14. Housing 24 has an inlet 26 and an outlet 28. A flow pathis disposed within the housing 24. A spring biased valve (not shown) isdisposed within the flow path in the shunt housing.

Siphon control device 16 has a second housing 30. Housing 30 has aninlet 32 and an outlet 34. Inlet 32 of siphon control device 16 is influid communication with outlet 28 of shunt 14. A primary flow path 36is disposed within second housing 30 and is in fluid communication withinlet 32 and outlet 34. The primary flow path has a generally axialorientation as shown by arrows A in FIG. 3A. A secondary flow path 38 isdisposed within the second housing 30 and is in fluid communication withinlet 32 and outlet 34. Secondary flow path 38 has a generally helicalorientation as shown by arrows B in FIGS. 2 and 3B. Secondary flow path38 has a higher resistance to fluid flow than primary path 36. Secondaryflow path 38 is always open.

A valve 40 is disposed within the primary flow path 36. Valve 40 has avalve seat 42 and a first ball 44 and a second ball 46. First ball 44 ismovable by gravity between a valve closed position, as shown in FIG. 3B,where the first ball 44 is in contact with valve seat 42, and a valveopen position, as shown in FIG. 3A, where the first ball 44 is spacedfrom valve seat 42. First ball 44 is disposed between the second ball 46and the valve seat 42. The second ball 46 is also movable by gravitybetween a valve closed position and a valve open position. Second ball46 is larger than first ball 44. Second ball 46 preferably weighs morethan first ball 44. The first ball 44 and the second ball 46 are biasedby gravity. First ball 44 is preferably made of ruby and the second ballis typically made of tantalum metal. Valve seat 42 is also preferablymade of ruby.

What is claimed is:
 1. A siphon guard comprising: a housing having aninlet and an outlet; a primary flow path disposed within the housing andin fluid communication with the inlet and the outlet; a secondary flowpath disposed within the housing and in fluid communication with theinlet and the outlet, the secondary flow path having a higher resistanceto fluid flow than the primary path; and a valve disposed within theprimary flow path, the valve having a valve seat and a first ball and asecond ball, the first ball being movable between a valve closedposition where the first ball is in contact with the valve seat and avalve open position where the first ball is spaced from the valve seat,the first ball is disposed between the second ball and the valve seat,the second ball being movable between a valve closed position and avalve open position.
 2. The siphon guard of claim 1, wherein the secondball is larger than the first ball.
 3. The siphon guard of claim 2,wherein the second ball is weighs more than the first ball.
 4. Thesiphon guard of claim 1, wherein the first ball and the second ball arebiased by gravity.
 5. The siphon guard of claim 1, wherein the secondflow path is always open.
 6. The siphon guard of claim 1, wherein thefirst ball is made of ruby and the second ball is made of tantalummetal.
 7. A shunt and siphon guard kit comprising: a shunt having afirst housing having an inlet and an outlet, a flow path disposed withinthe first housing; a spring biased valve being disposed within the flowpath in the shunt housing; a siphon guard having a second housing havingan inlet and an outlet, said inlet of the siphon guard being in fluidcommunication with the outlet of the shunt, a primary flow path disposedwithin the second housing and in fluid communication with the inlet andthe outlet, the primary flow path having an axial orientation, asecondary flow path disposed within the second housing and in fluidcommunication with the inlet and the outlet, the secondary flow pathhaving a higher resistance to fluid flow than the primary path; and avalve disposed within the primary flow path, the valve having a valveseat and a first ball and a second ball, the first ball being movable bygravity between a valve closed position where the first ball is incontact with the valve seat and a valve open position where the firstball is spaced from the valve seat, the first ball is disposed betweenthe second ball and the valve seat, the second ball being movable bygravity between a valve closed position and a valve open position. 8.The siphon guard of claim 7, wherein the second ball is larger than thefirst ball.
 9. The siphon guard of claim 8, wherein the second ball isweighs more than the first ball.
 10. The siphon guard of claim 7,wherein the first ball and the second ball are biased by gravity. 11.The siphon guard of claim 7, wherein the second flow path is alwaysopen.
 12. The siphon guard of claim 7, wherein the first ball is made ofruby and the second ball is made of tantalum metal.